Solid-state image pickup device

ABSTRACT

A solid-state image pickup device capable of suppressing the generation of dark current and/or leakage current is provided. The solid-state image pickup device has a first substrate provided with a photoelectric converter on its primary face, a first wiring structure having a first bonding portion which contains a conductive material, a second substrate provided with a part of a peripheral circuit on its primary face, and a second wiring structure having a second bonding portion which contains a conductive material. In addition, the first bonding portion and the second bonding portion are bonded so that the first substrate, the first wiring structure, the second wiring structure, and the second substrate are disposed in this order. Furthermore, the conductive material of the first bonding portion and the conductive material of the second bonding portion are surrounded with diffusion preventing films.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a Continuation of U.S. patent application Ser. No.16/242,835 filed Jan. 8, 2019; which is a Continuation of U.S. patentapplication Ser. No. 15/894,258 filed Feb. 12, 2018, now a U.S. patentSer. No. 10/217,786 issued Feb. 26, 2019; which is a Continuation ofco-pending U.S. patent application Ser. No. 15/456,386 filed Mar. 10,2017, now a U.S. Pat. No. 9,929,202 issued Mar. 27, 2018; which is aContinuation of U.S. application Ser. No. 15/209,605 filed Jul. 13,2016, now a U.S. Pat. No. 9,640,581 issued May 2, 2017; which is aContinuation of co-pending U.S. patent application Ser. No. 14/856,354,filed Sep. 16, 2015, now a U.S. Pat. No. 9,419,030 issued Aug. 16, 2016;which is a Divisional of co-pending U.S. patent application Ser. No.13/808,877 filed Jan. 7, 2013, now a U.S. Pat. No. 9,166,090 issued Oct.20, 2015; which is a National Phase application of InternationalApplication PCT/JP2011/003796, filed Jul. 4, 2011, which claims thebenefit of Japanese Patent Application No. 2010-156926, filed Jul. 9,2010. The disclosures of the above-named applications are herebyincorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a bonding portion of a solid-stateimage pickup device.

BACKGROUND ART

In CCD type and amplification-type solid-state image pickup devices usedfor digital still cameras, camcorders, and the like, in order to obtainhigh definition images, the sizes of pixels are required to be reduced.However, as the sizes of pixels are reduced more and more, a lightreceiving area of a photoelectric converter, in a pixel, detecting lightis decreased, and the sensitivity is decreased.

In PTL 1, a solid-state image pickup device has been disclosed in whichin a CMOS type solid-state image pickup device, which is anamplification-type solid-state image pickup device, in order to ensure alight receiving area of a photoelectric converter, a first substrateprovided with photoelectric converters and transfer transistors and asecond substrate provided with other circuits are bonded to each other.In PTL 1, for this bonding, a copper bonding pad is used for each pixel.

CITATION LIST Patent Literature

[PTL 1] Japanese Patent Laid-Open No. 2006-191081

SUMMARY OF INVENTION Technical Problem

However, according to the bonding method disclosed in PTL 1, copper maydiffuse from the copper bonding pad into the first substrate and/or thesecond substrate in some cases. When this metal impurity is mixed in asemiconductor region, a dark current and/or a leakage current may begenerated thereby, and as a result, a white spot and the like isgenerated on an image data to be obtained. In addition, when this metalimpurity is mixed in a semiconductor region forming a transistor, thegeneration of leakage current and/or variation of threshold value isliable to occur, and as a result, an operation failure may arise in somecases. In particular, in a solid image pickup device having several tensof thousands or more of pixels, that is, several tens of thousands ormore of bonding portions, serious contamination may start from thesebonding portions. A phenomenon as described above is liable to occurwhen a conductive material, such as copper, having a high diffusioncoefficient is used for the bonding portion.

Accordingly, the present invention provides a solid-state image pickupdevice capable of suppressing the generation of dark current and/orleakage current.

Solution to Problem

A solid-state image pickup device of the present invention, comprises afirst substrate provided with a photoelectric converter on its primaryface; a first wiring structure disposed on the primary face of the firstsubstrate and having a first bonding portion which contains a conductivematerial; a second substrate provided with, on its primary face, a partof a peripheral circuit including a control circuit and a readoutcircuit reading out a signal base on a charge of the photoelectricconverter; and a second wiring structure disposed on the primary face ofthe second substrate and having a second bonding portion which containsa conductive material, wherein the first bonding portion and the secondbonding portion are bonded to each other so that the first substrate,the first wiring structure, the second wiring structure, and the secondsubstrate are disposed in this order, and the conductive material of thefirst bonding portion and the conductive material of the second bondingportion are surrounded with diffusion preventing films.

Advantageous Effects of Invention

Accordingly, the present invention can provide a solid-state imagepickup device capable of suppressing the generation of dark currentand/or leakage current.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic cross-sectional view of a solid-state image pickupdevice according to Embodiment 1.

FIG. 2A is a schematic plan view of the solid-state image pickup deviceaccording to Embodiment 1.

FIG. 2B is a schematic plan view of the solid-state image pickup deviceaccording to Embodiment 1.

FIG. 3 is a circuit diagram of the solid-state image pickup deviceaccording to Embodiment 1.

FIG. 4A is a schematic cross-sectional view illustrating a step of amethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 4B is a schematic cross-sectional view illustrating a step of themethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 5A is a schematic cross-sectional view illustrating a step of themethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 5B is a schematic cross-sectional view illustrating a step of themethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 6A is a schematic cross-sectional view illustrating a step of themethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 6B is a schematic cross-sectional view illustrating a step of themethod for manufacturing the solid-state image pickup device accordingto Embodiment 1.

FIG. 7A is a schematic cross-sectional view of a bonding portion of thesolid-state image pickup device according to Embodiment 1.

FIG. 7B is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 1.

FIG. 7C is a schematic cross-sectional view of a bonding portion of thesolid-state image pickup device according to Embodiment 1.

FIG. 7D is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 1.

FIG. 8A is a schematic cross-sectional view of a bonding portion of asolid-state image pickup device according to Embodiment 2.

FIG. 8B is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 2.

FIG. 8C is a schematic cross-sectional view of a bonding portion of thesolid-state image pickup device according to Embodiment 2.

FIG. 8D is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 2.

FIG. 8E is a schematic cross-sectional view of a bonding portion of thesolid-state image pickup device according to Embodiment 2.

FIG. 8F is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 2.

FIG. 8G is a schematic cross-sectional view of a bonding portion of thesolid-state image pickup device according to Embodiment 2.

FIG. 8H is a schematic cross-sectional view of the bonding portion ofthe solid-state image pickup device according to Embodiment 2.

FIG. 9A is a schematic cross-sectional view illustrating a step of amethod for manufacturing the bonding portion according to Embodiment 2.

FIG. 9B is a schematic cross-sectional view illustrating a step of themethod for manufacturing the bonding portion according to Embodiment 2.

FIG. 9C is a schematic cross-sectional view illustrating a step of themethod for manufacturing the bonding portion according to Embodiment 2.

FIG. 10A is a schematic cross-sectional view of a bonding portion of asolid-state image pickup device according to Embodiment 3.

FIG. 10B is a schematic cross-sectional view of a bonding portion of thesolid-state image pickup device according to Embodiment 3.

FIG. 10C is a schematic cross-sectional view of a bonding portion of thesolid-state image pickup device according to Embodiment 3.

FIG. 11A is a schematic plan view illustrating a bonding portion of thesolid-state image pickup device according to Embodiment 3.

FIG. 11B is a schematic plan view illustrating a bonding portion of thesolid-state image pickup device according to Embodiment 3.

FIG. 11C is a schematic plan view illustrating a bonding portion of thesolid-state image pickup device according to Embodiment 3.

DESCRIPTION OF EMBODIMENTS

A solid-state image pickup device of the present invention has a firstsubstrate provided with photoelectric converters on its primary face, afirst wiring structure having first bonding portions, each of whichcontains a conductive material, a second substrate provided with a partof a peripheral circuit on its primary face, and a second wiringstructure having second bonding portions, each of which contains aconductive material. In addition, the first bonding portion and thesecond bonding portion are bonded to each other so that the firstsubstrate, the first wiring structure, the second wiring structure, andthe second substrate are disposed in this order. In this solid-stateimage pickup device, the conductive material of the first bondingportion and the conductive material of the second bonding portion aresurrounded with diffusion preventing films for the respective conductivematerials. By the structure as described above, the conductive materialsare surrounded with the respective diffusion preventing films even afterthe bonding, and hence a solid-state image pickup device capable ofsuppressing the generation of dark current and/or leakage current can beprovided.

Hereinafter, the present invention will be described in detail withreference to the drawings. In this embodiment, the primary face of thefirst substrate and the primary face of the second substrate aresubstrate surfaces on which transistors are formed. Opposite side faces(opposite side surface) facing the respective primary faces (primarysurfaces) are aback face (back surface) of the first substrate and aback face (back surface) of the second substrate. In addition, an upwarddirection indicates a direction from the back face toward the primaryface of the substrate, and a downward direction and a depth directioneach indicate a direction from the primary face toward the back face ofthe substrate. In the following descriptions, when the first and secondsubstrates are bonded with each other, the back face of the secondsubstrate is at the bottom face and the back face of the first substrateis at the top face.

In addition, a wire having a single damascene structure is formed by asingle damascene method in which a groove to be used for a wire isformed in an interlayer insulating film, and a conductive material, suchas a barrier metal or copper, is filled in the groove, so that a wireburied in the interlayer insulating film is obtained. A wire having adual damascene structure is formed such that a wire and a via areintegrally formed so as to be buried in an interlayer insulating film.That is, the wire having a dual damascene structure is formed by a dualdamascene method in which grooves to be used for a wire and a via areformed in an interlayer insulating film, and a conductive material, suchas a barrier metal or copper, is filled in the grooves.

Embodiment 1 of the present invention will be described with referenceto FIGS. 1 to 6B. First, a circuit of a solid-state image pickup deviceaccording to Embodiment 1 will be described with reference to FIG. 3. Inthis embodiment, the case in which a signal electric charge is anelectron will be described by way of example. The solid-state imagepickup device shown in FIG. 3 has a pixel portion 301 in which aplurality of photoelectric converters is arranged and a peripheralcircuit portion 302 having a peripheral circuit which includes a controlcircuit driving readout of a signal from the pixel portion 301 and asignal processing circuit processing a readout signal.

In the pixel portion 301, photoelectric converters 303, transfertransistors 304, amplification transistors 306, and reset transistors307 are arranged. A structure including at least one photoelectricconverter 303 is defined as a pixel. One pixel of this embodimentincludes one photoelectric converter 303, one transfer transistor 304,one amplification transistor 306, and one reset transistor 307. A sourceof the transfer transistor 304 is connected to the photoelectricconverter 303, and a drain region of the transfer transistor 304 isconnected to a gate electrode of the amplification transistor 306. Anode which is the same as the gate electrode of this amplificationtransistor 306 is defined as a node 305. The reset transistor 307 isconnected to the node 305 and sets the electric potential thereof to anarbitrary electric potential (such as, a reset electric potential). Inthis structure, the amplification transistor 306 is a part of a sourcefollower circuit and outputs a signal corresponding to the electricpotential of the node 305 to a signal line RL. The node 305 may also becalled a floating diffusion in some cases.

The peripheral circuit portion 302 indicates a region other than thepixel portion 301. In the peripheral circuit portion 302, a peripheralcircuit including a readout circuit and a control circuit is disposed.The peripheral circuit has a vertical scanning circuit VSR which is acontrol circuit supplying control signals to the gate electrodes of thetransistors of the pixel portion 301. In addition, the peripheralcircuit has a readout circuit RC which maintains signals outputted fromthe pixel portion 301 and performs signal processing, such asamplification, addition, and AD conversion. Furthermore, the peripheralcircuit has a horizontal scanning circuit HSR which is a control circuitcontrolling the timing for sequentially outputting signals from thereadout circuit RC.

In addition, the solid-state image pickup device according to Embodiment1 is formed by bonding two members to each other. The two members are afirst member 308 having a first substrate 101 and a second member 309having a second substrate 121. The photoelectric converters 303 and thetransfer transistors 304 of the pixel portion 301 are arranged on thefirst substrate, and the amplification transistors 306 and the resettransistors 307 of the pixel portion 301 and at least a part of theperipheral circuit are arranged on the second substrate. A controlsignal from the peripheral circuit of the second member 309 to the gateelectrode of the transfer transistor 304 of the first member 308 issupplied via a bonding portion 310. The structure of the bonding portion310 will be described later. A signal generated in the photoelectricconverter 303 of the first member 308 is read out at the drain region ofthe transfer transistor 304, that is, at the node 305. The node 305includes the structure formed in the first member 308 and the structureformed in the second member 309.

According to the structure as described above, compared to a relatedcase in which all the pixel portion is disposed on one member (that is,on one large substrate), the area of the photoelectric converter 303 canbe increased, and hence the sensitivity can be improved. In addition,compared to the related case in which all the pixel portion is disposedon one member (that is, on one large substrate), when the area of thephotoelectric converter is not changed, the number of the photoelectricconverters 303 can be increased, and hence the number of pixels can beincreased. In addition, compared to the related case in which all thepixel portion and all the peripheral circuit portion are disposed on onemember (that is, on one large substrate), it becomes easy to separatelyform the pixel portion and the peripheral circuit portion.

A specific plan layout of the solid-state image pickup device asdescribed above will be described using schematic plan views of asolid-state image pickup device shown in FIGS. 2A and 2B. FIG. 2A showsa plan layout of the first member 308, that is, the first substrate 101,and FIG. 2B shows a plan layout of the second member 309, that is, thesecond substrate 121.

In FIG. 2A, in the first member 308, there are disposed a pixel portion301A in which photoelectric converters are arranged and pad portions312A in each of which pads 313 are arranged. In the pixel portion 301A,the photoelectric converters 303, the transfer transistors 304, thebonding portions 310, and bonding portions 311 shown in FIG. 3 aredisposed. In addition, bonding portions 314A for connection to thesecond member 309 are disposed at the same position as those of the pads313 when viewed along a direction perpendicular to the primary face ofthe substrate 101. An external terminal is connected to the pad 313. Thepads 313 are disposed in the solid-state image pickup device and includepads, each of which outputs a signal (image signal) based on a chargegenerated in the photoelectric converter, and pads to each of which avoltage or the like supplied from the outside to drive the peripheralcircuit is inputted.

Next, in FIG. 2B, a pixel portion 301B, the peripheral circuit portion302, and pad portions 312B are disposed in the second member 309. Apartof a pixel circuit is disposed in the pixel portion 301B, and theamplification transistors 306, the reset transistors 307, and thebonding portions 310 and 311 shown in FIG. 3 are disposed therein. Apart of the peripheral circuit is disposed in the peripheral circuitportion 302, and the horizontal scanning circuits HSR, the verticalscanning circuits VSR, and the readout circuits RC are disposed therein.Bonding portions 314B for connection to the first member and protectivediode circuits 315 are disposed in the pad portions 312B.

In addition, the first member 308 and the second member 309 which havethe plan layouts shown in FIG. 2A and FIG. 2B, respectively, are bondedto each other to form the solid-state image pickup device of thisembodiment. In particular, the pixel portion 301A and the pixel portion301B are disposed so as to overlap with each other. In addition, thebonding portions 314A and the bonding portions 314B are bonded to eachother, and the bonding portions 310 and the bonding portions 311 of thefirst member are bonded to the bonding portions 310 and the bondingportions 311 of the second member, respectively. In addition, in FIGS.2A and 2B, a region of the first member 308 corresponding to aperipheral circuit portion 302B of the second member 309 is indicated bya peripheral circuit portion 302A. A part of the scanning circuit, thatis, a part of the peripheral circuit, may be disposed in the peripheralcircuit portion 302A. The structure of this bonding portion will bedescribed later in detail.

Next, the solid-state image pickup device shown in FIGS. 2A, 2B, and 3will be described with reference a schematic cross-sectional view shownin FIG. 1. In FIG. 1, the same constituent elements as those in FIGS.2A, 2B, and 3 are designated by the same reference numerals as thosedescribed above, and description will be omitted.

The first member 308 has a first wiring structure 149 and the firstsubstrate 101. The first substrate 101 is, for example, a siliconsemiconductor substrate and has a primary face 102 and a back face 103.The transistors are arranged on the primary face 102 of the firstsubstrate. The first wiring structure 149 has interlayer insulatingfilms 104 and 105, a gate electrode layer 107 containing gate electrodesand wires, wiring layers 109 and 110 containing wires, and a contactlayer 108 containing contacts and/or vias. In addition, the first wiringstructure 149 has a first diffusion preventing film 111. In thisembodiment, the numbers of the interlayer insulating film, the wiringlayer, and the contact layer included in the first wiring structure 149may be arbitrarily determined. In addition, the wiring layer 110 of thefirst wiring structure 149 contains the bonding portions 311 and 314Aand is integrated with a contact layer. Hereinafter, the bonding portionindicates a portion at which the conductive material of the first memberand the conductive material of the second member, which collectivelyform an electrical connection, are boned to each other and alsoindicates the conductive material before bonding.

In the pixel portion 301 of the first member 308, an n-typesemiconductor region 112 forming the photoelectric converter, an n-typesemiconductor region 114 functioning as the drain of the transfertransistor, and an element isolation structure 119 are disposed in thefirst substrate 101. The transfer transistor is formed of the n-typesemiconductor region 112, the n-type semiconductor region 114, and agate electrode 113 contained in the gate electrode layer 107. A chargestored in the n-type semiconductor region 112 is transferred to then-type semiconductor region 114 by the gate electrode 113. An electricpotential based on the charge transferred to the n-type semiconductorregion 114 is transmitted to the second member 309 via the contact ofthe contact layer 108, the wire of the wiring layer 109, and the wiringlayer 110 containing the contact layer. The wire contained in thiswiring layer 110 forms the bonding portion 311. In addition, thephotoelectric converter may be a buried photodiode further having ap-type semiconductor region or a photogate and may be appropriatelychanged.

A planarizing layer 115, a color filter layer 116 containing a pluralityof color filters, a planarizing layer 117, and a microlens layer 118containing a plurality of microlenses are disposed in this order in thepixel portion 301 at a back face 103 side of the first substrate 101. InFIG. 1, although each of the color filters and each of the microlensesare provided for one photoelectric converter, that is, are provided ineach pixel, one color filter and one microlens may be provided for aplurality of pixels. The solid-state image pickup device of thisembodiment is a so-called back-side illumination-type solid-state imagepickup device in which light is incident from a microlens layer 118 sideand is received by a photoelectric converter.

In the pad portion 312A of the first member 308, the pads 313 andopenings 100 which expose the pads 313 for connection to an externalterminal are provided. In addition, the bonding portions 314A, each ofwhich transmits a voltage inputted from the pad 313 to the second member309, are disposed. The bonding portions 314A are contained in the wiringlayer 110 as is the bonding portions of the pixel portion. In addition,in the first member 308, as shown in FIG. 1, an optional circuit element120 is provided in a region corresponding to the peripheral circuitportion 302B of the second member 309.

The second member 309 has a second wiring structure 150 and the secondsubstrate 121. The second substrate 121 is, for example, a siliconsemiconductor substrate and has a primary face 122 and a back face 123.The transistors are arranged on the primary face 102 of the secondsubstrate. The second wiring structure 150 has interlayer insulatingfilms 124 to 127, a gate electrode layer 128 containing gate electrodesand wires, wiring layers 130, 131, and 132 containing wires, and acontact layer 129 containing contacts and/or vias. In addition, thesecond wiring structure 150 has a second diffusion preventing film 133.In this embodiment, the numbers of the interlayer insulating film, thewiring layer, and the contact layer included in the second wiringstructure 150 may be arbitrarily determined. In addition, the wiringlayers 131 and 132 of the second wiring structure 150 are eachintegrated with a contact layer. In addition, the wiring layer 132contains the bonding portions 311 and 314B.

In the pixel portion 301 of the second member 309, a well 135 formingthe amplification transistor which forms the pixel circuit, an n-typesemiconductor region 138 forming source/drain regions of theamplification transistor, and an element isolation structure 136 aredisposed in the second substrate 121. The amplification transistor isdisposed in the well 135 and is formed of a gate electrode 137 containedin the gate electrode layer 128 and the n-type semiconductor region 138forming the source/drain regions. In this embodiment, the first member308 is connected to the gate electrodes 137 of the amplificationtransistors through the bonding portions 311. The bonding portion 311and the gate electrode 137 of the amplification transistor are connectedto each other through the wire and the via of the wiring layer 132, thewire and the via of the wiring layer 131, the wire of the wiring layer130, and the contact of the contact layer 129. In this case, the node305 shown in FIG. 3 is formed of the n-type semiconductor region 114,the wires and the vias of the wiring layers 109, 110, 132, 131, and 130,the contacts of the contact layers 108 and 129, and the gate electrode137 shown in FIG. 1. Other circuits (such as the reset transistor) ofthe pixel portion 301 are not shown in the figure.

Next, at least a part of the peripheral circuit including the controlcircuits, such as the horizontal scanning circuit and the verticalscanning circuit, and the readout circuits is disposed in the peripheralcircuit portion 302B of the second member 309. FIG. 1 shows an n-typetransistor and a p-type transistor in an optional circuit included inthe peripheral circuit. An n-type transistor formed of a gate electrode140 contained in the gate electrode layer 128 and n-type source/drainregions 141 is disposed in a p-type well 139. In addition, a p-typetransistor having a gate electrode 143 contained in the gate electrodelayer 128 and a p-type semiconductor region 144 forming p-typesource/drain regions is disposed in an n-type well 142.

In addition, in the pad portion 312B of the second member 309, there aredisposed the protective diode circuit 315 inputting a signal from thepad 313 of the first member 308 and the bonding portion 314B forconnection to the first member 308. The bonding portion 314B iscontained in the wiring layer 132 as is the bonding portion of the pixelportion. Two diodes 145 and 146 each formed from the semiconductorregion and two resistors 147 and 148 formed from the gate electrodelayer 128 are contained in the protective diode circuit 315 of thisembodiment. A commonly-used protective diode circuit can be applied tothis protective diode circuit 315.

In addition, in the solid-state image pickup device according to thisembodiment, the primary face 102 of the first substrate 101 and theprimary face 122 of the second substrate 121 are disposed to face eachother with the first and second wiring structures provided therebetween(facing arrangement). That is, the first substrate, the first wiringstructure, the second wiring structure, and the second substrate aredisposed in this order. In addition, it can also be said that an upperface of the first wiring structure 149 and an upper face of the secondwiring structure 150 are bonded to each other at a bonding plane X. Thatis, the first member 308 and the second member 309 are bonded to eachother at the bonding plane X. The bonding plane X is formed from theupper face of the first wiring structure 149 and the upper face of thesecond wiring structure 150. The bonding portions disposed in therespective members are bonded to each other at the bonding plane X andensure the conduction between the members. In addition, the pad 313 ofthe solid-state image pickup device for exchanging a signal with theoutside is disposed above the primary face 122 of the second member 309,and the opening 100 is provided at a first member 308 side.

In this embodiment, in the first wiring structure 149, the wiring layer109 is formed of wires (aluminum wires) primarily composed of aluminum,and the wiring layer 110 is formed of wires (copper wires) primarilycomposed of copper and has a dual damascene structure. In addition, inthe second wiring structure 150, the wiring layer 130 is formed ofcopper wires and has a single damascene structure. The wiring layers 131and 132 are formed of copper wires and each have a dual damascenestructure. The bonding portion 311 and the bonding portion 314A formedof the wires contained in the wiring layer 110 are bonded to the bondingportion 311 and the bonding portion 314B formed of the wires containedin the wiring layer 132, respectively, at the bonding plane X by metalbonding. In addition, in the pad portion, the pad 313 for connection toan external terminal is disposed in the same layer as that of the wiringlayer 109, that is, at the same height as that thereof, and is aconductive material primarily composed of aluminum. The height of thiswiring layer 109 and that of the pad 313 are each a height from theprimary face 102 of the first substrate 101.

Next, a method for manufacturing the solid-state image pickup device ofthis embodiment will be described with reference to FIGS. 4A to 6B.FIGS. 4A and 4B are each a schematic cross-sectional view showing a stepof manufacturing the first member 308, FIGS. 5A and 5B are each aschematic cross-sectional view showing a step of manufacturing thesecond member 309, and FIGS. 6A and 6B are each a schematiccross-sectional view showing a manufacturing step performed after thefirst member 308 and the second member 309 are bonded to each other.

Steps of manufacturing the first member 308 shown in FIG. 1 will bedescribed with reference to FIGS. 4A and 4B. In FIGS. 4A and 4B, astructure to be later formed into the first member 308 shown in FIG. 1is represented by 308′, and portions to be formed into the pixel portion301, the peripheral circuit portion 302, the pad portion 312, and thecircuit element 120, which is a part of the peripheral circuit, shown inFIG. 1 are represented by 301′, 302′, 312′, and 120′, respectively.

First, a semiconductor substrate is provided, and elements are formed inthe semiconductor substrate. A semiconductor substrate 401 of athickness D3 having a primary face 402 and a back face 403 is provided.The semiconductor substrate 401 is, for example, a silicon semiconductorsubstrate. The element isolation structure 119 is formed in thesemiconductor substrate 401. The element isolation structure 119contains an insulating material, such as a silicon oxide film, and has,for example, a LOCOS or an STI structure. In addition, a well (notshown) having an arbitrary conductivity type is formed in thesemiconductor substrate 401. Subsequently, the n-type semiconductorregions 112 and 114 and a p-type semiconductor region (not shown), whichforma photoelectric converter and a transistor, are formed. In addition,the gate electrode layer 107 containing the gate electrode 113 of thetransfer transistor is formed. The gate electrode layer is formed, forexample, by deposition and patterning of a polysilicon layer and maycontain a wire as well as the gate electrode. Methods for forming thegate electrode, element isolation, and semiconductor region may beperformed in accordance with a general semiconductor process, anddetailed description will be omitted. The structure shown in FIG. 4A isobtained by the steps described above.

Next, the wiring structure is formed on the primary face 402 of thesemiconductor substrate 401. In particular, first, a film to be formedinto an interlayer insulating film 104′ is formed so as to cover thegate electrode layer 107. After contact holes are formed in the film tobe formed into an interlayer insulating film 104′, films of a barriermetal and tungsten are formed, and excessive parts of the films thereofare removed, thereby forming the interlayer insulating film 104′ and thecontact layer 108. In addition, films of a barrier metal and aluminumare formed on the interlayer insulating film 104′, followed bypatterning, so that the wiring layer 109 is formed. Next, a film to beformed into the interlayer insulating film 105 is formed so as to coverthe wiring layer 109, and a film to be formed into the first diffusionpreventing film 111 is formed. Next, the wiring layer 110 is formed by adual damascene method. Grooves for wires and grooves (holes) for viasare formed in a laminate of the film to be formed into the interlayerinsulating film 105 and the film to be formed into the first diffusionpreventing film 111. A film of a barrier metal having a diffusionpreventing function and a film of copper are formed so as to fill thegrooves. The wiring layer 110 is formed by removing excessive barriermetal and copper, and the interlayer insulating film 105 and the firstdiffusion preventing film 111 are formed. In this case, the firstdiffusion preventing film 111 has openings to expose wires. In addition,the first diffusion preventing film 111 can be simultaneously planarizedby etching or chemical mechanical polishing (CMP) performed when abarrier metal and copper are removed. The upper face of the firstplanarized diffusion preventing film 111 thus planarized has asufficient flatness for subsequent bonding. The upper face of the wiringstructure is formed of the upper face of the first diffusion preventingfilm 111 and the upper face of wiring layer 110. The interlayerinsulating film 104′ is later formed into the interlayer insulating film104 shown in FIG. 1.

In this embodiment, the interlayer insulating films 104′ and 105 areeach a silicon oxide film. However, the interlayer insulating films 104′and 105 may also be formed, for example, of a silicon nitride film or anorganic resin. The contact 108 is formed, for example, from tungsten.The wiring layer 110 contains the bonding portion 314A and a bondingportion 311A, and the wiring layer 109 contains the pad 313. The barriermetal has a function to prevent diffusion of copper which is aconductive material and is formed, for example, of tantalum or tantalumnitride. The first diffusion preventing film 111 is formed of a filmwhich has a diffusion preventing function to the conductive material ofthe wiring layer 110 containing the bonding portion and is ahigh-density inorganic insulating film. For example, the diffusionpreventing film is a silicon nitride film or a silicon carbide film.Methods for manufacturing these wiring layer, contact layer, andinterlayer insulating film can be performed in accordance with a generalsemiconductor process, and detailed description will be omitted. Thestructure shown FIG. 4B is obtained by the steps described above. InFIG. 4B, the portions represented by reference numerals 104′, 105, 106,108, 109, and 110 are later used to form the first wiring structure 149shown in FIG. 1. In addition, the bonding portion 311A later forms thebonding portion 311. In this FIG. 4B, the upper face of the first wiringstructure 149 which later forms the bonding plane X shown in FIG. 1 isformed of the upper face of the first diffusion preventing film 111 andthe upper face of each wire of the wiring layer 110. The structure ofthis upper face will be described later in detail.

Next, steps of manufacturing the second member 309 shown in FIG. 1 willbe described with reference to FIGS. 5A and 5B. In FIGS. 5A and 5B, astructure to be later formed into the second member 309 shown in FIG. 1is represented by reference numeral 309′, and portions to be formed intothe pixel portion 301, the peripheral circuit portion 302, the padportion 312, and the protective diode circuit 315 shown in FIG. 1 arerepresented by reference numerals 301′, 302′, 312′, and 315′,respectively.

Next, a wiring structure is formed on a primary face 405 of asemiconductor substrate 404. In particular, first, a film to be formedinto the interlayer insulating film 124 is formed so as to cover thegate electrode 128. After contact holes are formed in the film to beformed into the interlayer insulating film 124, a film of a barriermetal and a film of tungsten are formed, and the interlayer insulatingfilm 124 and the contact layer 129 are formed by removing excessiveparts of the films of a barrier metal and tungsten. In addition, a filmto be formed into the interlayer insulating film 125 is formed on theinterlayer insulating film 124. Next, the wiring layer 130 is formed bya single damascene method. Grooves for wire are formed in the film to beformed into the interlayer insulating film 125, and a film of a barriermetal having a diffusion preventing function and a film of copper areformed so as to fill the grooves. The wiring layer 130 is formed byremoving excessive barrier metal and copper, and the interlayerinsulating film 125 is formed. Next, a film to be formed into theinterlayer insulating film 126 is formed so as to cover the interlayerinsulating film 125 and the wiring layer 130. In addition, the wiringlayer 131 is formed by a dual damascene method. In particular, groovesfor wires and vias are formed in the film to be formed into theinterlayer insulating film 126. A film of a barrier metal having adiffusion preventing function and a film of copper are formed so as tofill the grooves. The wiring layer 131 is formed by removing excessivebarrier metal and copper, and the interlayer insulating film 126 isformed. In addition, a film to be formed into the interlayer insulatingfilm 127 and a film to be formed into the second diffusion preventingfilm 133 are formed so as to cover the interlayer insulating film 126and the wiring layer 131. Next, the wiring layer 132 is formed by a dualdamascene method. That is, grooves for wires and vias are formed in thefilms to be formed into the interlayer insulating film 127 and thesecond diffusion preventing film 133, and a film of a barrier metalhaving a diffusion preventing function and a film of copper are formedso as to fill the grooves. The wiring layer 132 is formed by removingexcessive parts of the film of copper and the film of a barrier metalhaving a diffusion preventing function. In this case, the barrier metalhas a diffusion preventing function to copper which is a conductivematerial and is formed, for example, of tantalum or tantalum nitride. Inaddition, the interlayer insulating film 127 and the second diffusionpreventing film 133 are formed. In this embodiment, the second diffusionpreventing film 133 has openings so as to expose wires. In addition, thesecond diffusion preventing film 133 can be simultaneously planarized byetching or CMP performed when a barrier metal and copper are removed.The upper face of the wiring structure is formed of the upper face ofthe second diffusion preventing film 133 and the upper face of thewiring layer 132.

In this case, although being formed of silicon oxide, the interlayerinsulating films 124 to 127 each may also be formed, for example, of asilicon nitride film or an organic resin. The contact 129 is formed, forexample, of tungsten. The wiring layer 130 is formed of wires primarilycomposed of copper and has a single damascene structure. The wiringlayers 131 and 132 are each formed of wires primarily composed of copperand each have a dual damascene structure. The wiring layer 132 containsthe bonding portion 314B and a bonding portion 311B. Methods formanufacturing these wiring layer, contact layer, and interlayerinsulating film can be performed in accordance with a generalsemiconductor process, and more detailed description will be omitted.The structure shown in FIG. 5B is obtained by the steps described above.In FIG. 5B, the portions represented, for example, by reference numerals124 to 127 and 129 to 133 are later used to form the second wiringstructure 150 shown in FIG. 1. In addition, the bonding portion 311Blater forms the bonding portion 311.

In this FIG. 5B, the upper face of the second wiring structure 150 whichlater forms the bonding plane X shown in FIG. 1 is formed of the upperface of the interlayer insulating film 127 and the upper face of eachwire of the wiring layer 132. The wiring layer 132 is also a conductivematerial used as the bonding portion. That is, the upper face of thesecond wiring structure 150 contains the upper face of the conductivematerial. The structure of this upper face will be described later indetail.

The first member 308′ and the second member 309′ as shown in FIGS. 4Band 5B, respectively, are bonded together so that the primary face 402and the primary face 405 of the respective semiconductor substrates faceeach other. That is, the uppermost face of the wiring structure of thefirst member 308′ and the uppermost face of the wiring structure of thesecond member 309′ are boned to each other. In this embodiment, sincethe bonding portions 311A and 311B and the bonding portions 314A and314B are formed of wires primarily composed of copper, when bonding isperformed therebetween, metal bonding of copper may be performed. Inaddition, bonding is preferably performed in a vacuum or an inert gasatmosphere. Furthermore, before bonding is performed, plasma irradiationis preferably performed on the upper face of each wiring structure. Byperforming this plasma irradiation, compared to the case in which plasmairradiation is not performed, bonding between the interlayer insulatingfilms, such as a silicon oxide film and/or a silicon nitride film, canbe more strengthened. In addition, instead of using plasma irradiation,an activation method by a chemical treatment may also be used. By thisbonding, the two wiring structures are united into one wiring structurewhich includes the copper bonding portions surrounded with the diffusionpreventing films.

In addition, after the first member 308′ and the second member 309′ arebonded together, the thickness of the semiconductor substrate 401 of thefirst member 308′ is reduced at a back face 403 side. The reduction ofthe thickness may be performed by CMP or etching. Accordingly, thesemiconductor substrate 401 is formed into a semiconductor substrate407, and the thickness is changed from D3 to D1 (D1<D3) (FIG. 6A). Asdescribed above, since the thickness of the semiconductor substrate 401is reduced to form the semiconductor substrate 407, subsequently,incident light is able to efficiently enter the photoelectric converter.In addition, at this stage, the thickness D1 of the semiconductorsubstrate 407 is smaller than a thickness D4 of the semiconductorsubstrate 404.

Next, a planarizing layer 409 formed of a resin, a color filter layer410, a planarizing layer 411 formed of a resin, and a microlens layer412 are formed in this order on a back face 408 of the semiconductorsubstrate 407. Methods for manufacturing these planarizing layer, colorfilter layer, and microlens layer can be performed in accordance with ageneral semiconductor process, and detailed description will be omitted.In this case, the microlens layer may be formed to the region 312′ whichis to be formed into the pad portion. The structure shown in FIG. 6B isobtained by the steps described above.

In addition, the opening 100 is formed to expose the pad 313. In thisstep, a photoresist mask having an arbitrary opening is formed on themicrolens layer 412 using a photolithographic technique. In addition,using a dry etching technique, the microlens layer 412, the planarizinglayer 411, the color filter layer 410, the planarizing layer 409, thesemiconductor substrate 407, and the interlayer insulating film 104′ arepartially removed, thereby forming the opening 100 to expose the pad313.

Accordingly, the microlens layer 118, the planarizing layers 117 and115, the color filter layer 116, the first substrate 101, and theinterlayer insulating film 104 are formed. As a result, the structureshown in FIG. 1 is obtained. The semiconductor substrate 404, theprimary face 405, aback face 406, and the thickness D4 shown in FIG. 6Bcorrespond to the second substrate 121, the primary face 122, the backface 123, and the thickness D2 shown in FIG. 1, respectively. Althoughthe thickness D4 is not changed from the thickness D2 in this case, thethickness of the semiconductor substrate 404 may be reduced so that thethickness D2 is smaller than the thickness D4. Although the number ofsteps is increased by the reduction in thickness, the solid-state imagepickup device can be miniaturized.

Hereinafter, the details of the bonding portion will be described withreference to FIGS. 7A to 7D. FIGS. 7A to 7D are each an enlargedschematic cross-sectional view of the bonding portion 311 shown inFIG. 1. In FIGS. 7A to 7D, the same constituent elements as those shownin FIGS. 1 to 6B are designated by the same reference numerals as thosedescribed above, and description will be omitted.

First, FIG. 7A shows the state before the first member and the secondmember are bonded to each other, and FIG. 7B shows the state in whichthe two members are bonded to each other (FIG. 6A). The first member308′ has the wiring layer 109, the wiring layer 110, and the firstdiffusion preventing film 111. The wring layer 109 contains aluminum 109a and a barrier metal 109 b, and the wiring layer 110 contains copper110 a and a barrier metal 110 b. In addition, the second member 309′ hasthe wiring layer 131, the wiring layer 132, and the second diffusionpreventing film 133. The wiring layer 131 contains copper 131 a and abarrier metal 131 b, and the wiring layer 132 contains copper 132 a anda barrier metal 132 b. That is, the bonding portion contains copperhaving a higher diffusion coefficient than that of aluminum as aconductive material. In this case, the conductive material is notlimited to copper and may be selected from alloys primarily composed ofcopper, other metals, such as Au, and alloys thereof. In addition, abarrier metal for copper functions as a diffusion preventing film havinga capability of preventing diffusion of copper. As this barrier metal,for example, metals, such as a tantalum, manganese, niobium, andchromium, and alloys thereof may be mentioned, and a tantalum nitridefilm also has a barrier function. In addition, as the first diffusionpreventing film and the second diffusion preventing film, for example, asilicon nitride film, a silicon carbide film, silicon carbonitride film,or a silicon oxynitride film may be mentioned. In addition, the copper110 a is surrounded with the barrier metal 110 b except for the portionexposed to a plane X1. Furthermore, the copper 132 a is surrounded withthe barrier metal 132 b except for the portion exposed to a plane X2. Inthis embodiment, the plane X1 is the upper face of the first wiringstructure 149, and the plane X2 is the upper face of the second wiringstructure 150.

As shown in FIG. 7B, the plane X1 and the plane X2 form the bondingplane X, and the first member 308′ and the second member 309′ are bondedto each other. The copper 110 a and the copper 132 a are metal-bondedtogether. In this case, the copper 110 a and the copper 132 a aresurrounded with the barrier metal 110 b and the barrier metal 132 b,respectively, each of which is the diffusion preventing film having adiffusion preventing function to copper. According to the structure asdescribed above, since the conductive material is surrounded with thediffusion preventing film at the bonding portion, a solid-state imagepickup device capable of suppressing the generation of dark currentand/or leakage current can be provided.

FIG. 7C is a schematic cross-sectional view showing the case in which inthe structure shown in FIG. 7A, the positions of the wiring layer 110and the wiring layer 132, which form the bonding portion, are shifted.In the case as shown in FIG. 7C, since the first diffusion preventingfilm 111 and the second diffusion preventing film 133 are provided, theconductive material can also be surrounded with the diffusion preventingfilms at the bonding portion. In particular, as shown in FIG. 7D, thecopper 110 a and the copper 132 a are collectively surrounded with thebarrier metal 110 b and the barrier metal 132 b, each of which is thediffusion preventing film, and the first diffusion preventing film 111and the second diffusion preventing film 133. By the structure asdescribed above, even if the position is shifted, for example, byvariation in process condition, the conductive materials are surroundedwith the diffusion preventing films at the bonding portion; hence, asolid-state image pickup device capable of suppressing the generation ofdark current and/or leakage current can be provided.

The present invention is not limited to the steps described in themanufacturing method according to this embodiment, and the order of thesteps may also be changed. In addition, the order of manufacturing thefirst member 308 and the second member 309 may be appropriatelydetermined. An SOI substrate may also be applied to each of thesemiconductor substrates 401 and 404. In addition, it is also possiblethat the first member 308 and the second member 309 are separatelypurchased as the substrates for the solid-state image pickup device andare then bonded together.

Next, Embodiment 2 of the present invention will be described withreference to FIGS. 8A to 9C. In this embodiment, several modificationsof the structure of the bonding portion will be described. FIGS. 8A to8H are each a schematic cross-sectional view focusing on a bondingportion corresponding to that shown in FIGS. 7A to 7D. In FIGS. 8A to8H, constituent elements similar to those shown in FIGS. 1 to 7D aredesignated by the same reference numerals as those described above, anddescription will be omitted.

First, the modification of the bonding portion shown in FIGS. 8A and 8Bwill be described. FIG. 8A is a schematic cross-sectional viewcorresponding to that shown in FIG. 7A, and FIG. 8B is a schematiccross-sectional view corresponding to that shown in FIG. 7B. In FIG. 8A,the differences from FIG. 7A are that the wiring layer 110 has a smallerexposed area than that of the wiring layer 132 and that the secondmember 309′ has no second diffusion preventing film 133. Although thestructure shown in FIG. 8A is only a partial cross-section thereof, thearea of the wiring layer 110 at the plane X1 is smaller than the area ofthe wiring layer 132 at the plane X2. In the structure as describedabove, as shown in FIG. 8B illustrating the state after bonding, thecopper 110 a and the copper 132 a are also surrounded with the barriermetals 110 b and 132 b, each of which is the diffusion preventing film,and the first diffusion preventing film 111.

Next, the modification of the bonding portion shown in FIGS. 8C and 8Dwill be described. FIG. 8C is a schematic cross-sectional viewcorresponding to that shown in FIG. 8A, and FIG. 8D is a schematiccross-sectional view corresponding to that shown in FIG. 8B. In FIG. 8C,the difference from FIG. 8A is that the wiring layer 110 has a concaveportion 801 at the plane X1. In particular, the first diffusionpreventing film 111 is disposed on the interlayer insulating film 105and the wiring layer 110 and has an opening corresponding to the wiringlayer 110. In the structure as described above, as shown in FIG. 8Dillustrating the state after bonding, the copper 110 a and the copper132 a are also surrounded with the barrier metals 110 b and 132 b, eachof which is the diffusion preventing film, and the first diffusionpreventing film 111. In this modification, although the concave portion801 has a step corresponding to the thickness of the first diffusionpreventing film 111, the step may be increased, for example, bypartially removing the copper 110 a. In addition, even if the wiringlayer 110 has the concave portion 801, since the coefficient of thermalexpansion of a conductive material, such as copper, is larger than thatof a dielectric material forming a diffusion preventing film and aninterlayer insulating film, the bonding plane X of the bonding may havea flat face as shown in FIG. 8D.

Next, the modification of the bonding portion shown in FIGS. 8E and 8Fwill be described. FIG. 8E is a schematic cross-sectional viewcorresponding to that shown in FIG. 8C, and FIG. 8F is a schematiccross-sectional view corresponding to that shown in FIG. 8D. In FIG. 8E,the difference from FIG. 8C is that the wiring layer 110 has a convexportion 802 at the plane X1. In particular, the copper 110 a has aconvex portion protruding by a thickness D from the plane X1 formed ofthe first diffusion preventing film 111 and the like. In the structureas described above, as shown in FIG. 8F illustrating the state afterbonding, the copper 110 a and the copper 132 a are also surrounded withthe barrier metals 110 b and 132 b, each of which is the diffusionpreventing film, and the first diffusion preventing film 111. In thecase described above, although having a smooth shape, the convex portion802 may have a rectangular shape. In addition, since the pressure isapplied for bonding, even if the wiring layer 110 has the convex portion802, the bonding plane X after the bonding may have a flat face as shownin FIG. 8F.

Next, the modification of the bonding portion shown in FIGS. 8G and 8Hwill be described. FIG. 8G is a schematic cross-sectional viewcorresponding to that shown in FIG. 8E, and FIG. 8H is a schematiccross-sectional view corresponding to that shown in FIG. 8F. In FIG. 8G,the differences from FIG. 8E is the following three points. That is, thethree points are that the wiring layer 132 also has a convex portion 803at the plane X2, the area of the wiring layer 110 at the plane X1 andthe area of the wiring layer 132 at the plane X2 are equal to eachother, and the second member 309′ has the second diffusion preventingfilm 133. The copper 110 a has a convex portion protruding from theplane X1 by a thickness D1, and the copper 132 a has a convex portionprotruding from the plane X2 by a thickness D2. In the structure asdescribed above, as shown in FIG. 8H illustrating the state afterbonding, the copper 110 a and the copper 132 a are also surrounded withthe barrier metals 110 b and 132 b, each of which is the diffusionpreventing film, the first diffusion preventing film 111, and the seconddiffusion preventing film 133. In this case, a gap 804 is formed betweenthe first member 308′ and the second member 309′. Since the copper 110 aand the copper 132 a are in contact with the gap 804, copper may diffuseat the interface with this gap 804 in some cases. However, since thefirst diffusion preventing film 111 and the second diffusion preventingfilm 133 are provided, diffusion of copper to the substrate sides of thefirst member 308′ and the second member 309′ can be suppressed. Ofcourse, the gap 804 may not be formed in some cases after the firstmember 308′ and the second member 309′ shown in FIG. 8G are bondedtogether.

As described above, also in the structures as shown in FIGS. 8A to 8H,copper can be surrounded with the diffusion preventing film at thebonding portion. Hence, a solid-state image pickup device capable ofsuppressing the generation of dark current and/or leakage current can beprovided.

Hereinafter, a formation method of a bonding portion having the convexportion shown in each of FIGS. 8E and 8G will be described focusing onthe bonding portion 311B shown in FIG. 8G. First, the interlayerinsulating film 126, the wiring layer 131, and the interlayer insulatingfilm 127 are formed. Subsequently, the wiring layer 132 is formed in theinterlayer insulating film 127 by a dual damascene method. In this case,when excessive films of copper and barrier metal are removed, the copper132 a having a convex portion (a protrusion portion) can be formed byadjusting a polishing speed and a slurry in the case of using a CMPmethod or by adjusting an etching gas and the like in the case of usingetching (FIG. 9A). Next, a film 133′ which covers the convex portion andwhich is to be formed into the second diffusion preventing film isformed (FIG. 9B) and is then partially removed by etching method or CMPmethod, so that the second diffusion preventing film 133 and the convexportion 803 can be formed (FIG. 9C).

In addition, in FIGS. 9A to 9C, the interlayer insulating film 126 andthe interlayer insulating film 127 are each formed of a plurality ofinsulating films, and a diffusion preventing film 701 covering the upperface of the wiring layer 131 is formed. As described above, thestructure of the interlayer insulating film may be appropriatelydetermined.

Hereinbefore, in this embodiment, the modifications of the structure ofthe bonding portion are described. The modifications described above maybe appropriately used in combination and may be appropriately applied toat least one of the first member and the second member.

Next, Embodiment 3 of the present invention will be described withreference to FIGS. 10A to 11C. In this embodiment, several modificationsof the structure of the bonding portion will be described. FIGS. 10A to100 are schematic cross-sectional views of the bonding portionsdescribed with reference to FIGS. 8A to 8H. In FIGS. 10A to 100,constituent elements similar to those shown in FIGS. 1 to 7D aredesignated by the same reference numerals as those described above, anddescription will be omitted.

FIGS. 10A and 10B correspond to each other and are each a schematiccross-sectional view in which a plurality of bonding portions shown inFIG. 8B or 8D is arranged. FIG. 10C shows the modification of thestructure shown in FIG. 10B.

First, in FIG. 10A, the first diffusion preventing film 111 is formedcommon to a plurality of the bonding portions 311. In FIG. 10B, a firstdiffusion preventing film 111P is formed by patterning so as to surroundthe periphery of the corresponding bonding portion, and the firstdiffusion preventing film 111 between the bonding portions 311 isremoved. In addition, compared to the structure shown in FIG. 10B, inFIG. 10C, a second diffusion preventing film 133P is further provided,and the second diffusion preventing film 133P is formed by patterning soas to surround the periphery of the corresponding bonding portion as inthe case of the first diffusion preventing film 111P.

In this case, since the first diffusion preventing film is formed of asilicon nitride film, and the interlayer insulating film is formed ofsilicon oxide, the first diffusion preventing film has a dielectricconstant higher than that of the interlayer insulating film. When a filmhaving a high dielectric constant as described above is disposed alongthe periphery of a wire, the parasitic capacitance thereof is increased.Hence, compared to the structure shown in FIG. 10A, the parasiticcapacitance between wires can be reduced by the structure shown in FIG.10B. In addition, also in the case in which the second diffusionpreventing film 133P is provided as shown in FIG. 10C, the parasiticcapacitance can be reduced. The diffusion preventing film 701 may alsobe patterned as shown in FIGS. 10B and 100.

FIGS. 11A to 11C are each a schematic plan view of an outer edge of eachstructure to illustrate the positional relationship of the wiring layer110, the wiring layer 132, the first diffusion preventing film, and thesecond diffusion preventing film at the bonding portion 311. In otherwords, these views show the arrangement of each structure at the bondingplane X. In FIGS. 11A to 11C, constituent elements similar to thoseshown in FIGS. 1 to 100 are designated by the same reference numerals asthose described above, and description will be omitted.

FIG. 11A is a schematic plan view corresponding to FIG. 10B. The lineXB-XB shown in FIG. 11A corresponds to the cross-section taken along thebonding plane X of FIG. 10B. As shown in FIG. 11A, the first diffusionpreventing film 111P has the largest area and covers the wiring layer132. That is, a face at which copper of the wiring layer 132 is exposedcorresponds to the first diffusion preventing film 111P and the wiringlayer 110. By the size relationship between the patterns as describedabove, copper can be easily covered with the diffusion preventing film.

FIG. 11B and FIG. 11C are schematic plan views corresponding to FIG.10C. The line XC-XC shown in FIG. 11B and FIG. 11C corresponds to thecross-section taken along the bonding plane X shown in FIG. 10C. In FIG.11B, the size of the pattern is increased from the wiring layer 110, thewiring layer 132, the first diffusion preventing film 111P, and thesecond diffusion preventing film 133P in this order. By the sizerelationship between the patterns as described above, a face at whichcopper of the wiring layer 132 is exposed corresponds to the firstdiffusion preventing film 111P and the wiring layer 110, and copper canbe easily covered with the diffusion preventing film.

FIG. 11C has different patterns of the wiring layer 110 and the wiringlayer 132 from those shown in FIG. 11B. The patterns of the wiring layer110 and the wiring layer 132 have long sides in a first direction and asecond direction different therefrom, respectively. By the patterns asdescribed above, the acceptable range of the positional shift at thebonding can be increased.

As described in this embodiment, the first diffusion preventing film,the second diffusion preventing film, and the bonding portion each mayhave an arbitrary shape, and the shapes thereof may be appropriatelyselected.

Hereinafter, as one application example of the solid-state image pickupdevice of each of the above embodiments, an image pickup systemincorporating a solid-state image pickup device will be described by wayof example. In the image pickup system, besides devices, such as acamera, primarily used to pickup images, devices (such as a personalcomputer and a personal digital assistant) auxiliary having an imagepickup function are also included. For example, a camera includes thesolid-state image pickup device of the present invention and aprocessing portion which processes a signal outputted from thesolid-state image pickup device. This processing portion may include,for example, an A-D converter and a processor processing a digital dataoutputted therefrom.

As has thus been described, according to the solid-state image pickupdevice of the present invention, a solid-state image pickup devicecapable of suppressing the generation of dark current and/or leakagecurrent can be provided.

In addition, the present invention is not limited to the structuresdescribed in the specification and may also be applied to the case inwhich the pixel circuit is changed and only the photoelectric convertersare arranged for the first member. Furthermore, the present inventionmay be appropriately applied, for example, to the structure in which theconductive and/or circuit type is changed to a reversed type, thestructure in which a wiring layer and an interlayer insulating film arefurther provided, and the case in which a single damascene structure ischanged to a dual damascene structure. In addition, the structures ofthe embodiments may also be used in combination.

Furthermore, the present invention is not limited to a solid-state imagepickup device and may also be applied to common semiconductor devices,such as a DRAM.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

REFERENCE SIGNS LIST

-   301 pixel portion-   302 peripheral circuit portion-   308 first member-   309 second member-   149 first wiring structure-   150 second wiring structure-   311 bonding portion-   314 bonding portion-   101 first substrate-   121 second substrate-   X bonding plane-   111 first diffusion preventing film-   133 second diffusion preventing film

1. A device comprising: a first substrate; a second substrate whichoverlaps the first substrate; a first structure which is between thefirst substrate and the second substrate, the first structure includinga first film of a dielectric material and a first portion of aconductive material, the first portion being in a groove of the firstfilm; and a second structure which is between the first structure andthe second substrate, the second structure including a second film of adielectric material and a second portion of a conductive material, thesecond portion being in a groove of the second film, wherein the firstfilm is bonded to the second film, and the first portion is bonded tothe second portion, and wherein the first film includes an insulatingfilm which is a silicon nitride film or a silicon carbide film.
 2. Thedevice according to claim 1, wherein the insulating film of the firstfilm is a first insulating film, and wherein the second film includes asecond insulating film which is a silicon nitride film or a siliconcarbide film, and the groove of the second film is formed by at leastthe second insulating film.
 3. The device according to claim 1, whereinthe groove of the first film is formed by at least the insulating film.4. The device according to claim 1, wherein the insulating film has apart between the second portion and the first substrate.
 5. The deviceaccording to claim 2, wherein the second insulating film has a partbetween the first portion and the second substrate.
 6. The deviceaccording to claim 1, wherein the first substrate is provide with afirst transistor, and the second substrate is provide with a secondtransistor.
 7. The device according to claim 6, wherein the firstportion is connected to the first transistor, and the second portion isconnected to the second transistor.
 8. The device according to claim 1,wherein the first film includes a first silicon oxide film, the secondfilm includes a second silicon oxide film, and the first silicon oxidefilm is bonded to the second silicon oxide film.
 9. The device accordingto claim 1, wherein the silicon nitride film is a silicon carbonitridefilm or a silicon oxynitride film.
 10. A system comprising: the deviceaccording to claim 1; and a processor which processes a digital databased on a signal outputted from the device.
 11. A device comprising: afirst substrate; a second substrate which overlaps the first substrate;a first structure which is between the first substrate and the secondsubstrate, the first structure including a first film of a dielectricmaterial and a first portion of a conductive material, the first portionbeing in a groove of the first film; and a second structure which isbetween the first structure and the second substrate, the secondstructure including a second film of a dielectric material and a secondportion of a conductive material, the second portion being in a grooveof the second film, wherein the first film is bonded to the second film,and the first portion is bonded to the second portion, and wherein thefirst film includes a first insulating film of a first dielectricmaterial, the first film includes a second insulating film of a seconddielectric material other than the first dielectric material, the secondinsulating film is between the first insulating and the first substrate.12. The device according to claim 11, wherein the second film includes athird insulating film of a third dielectric material, the second filmincludes a fourth insulating film of a fourth dielectric material otherthan the third dielectric material, the fourth insulating film isbetween the third insulating and the second substrate.
 13. The deviceaccording to claim 12, wherein the first structure includes a first wirebetween the first portion and the first substrate, the first wire isbetween the second insulating film and the first substrate, the secondstructure includes a second wire between the second portion and thesecond substrate, and the second wire is between the fourth insulatingfilm and the second substrate.
 14. The device according to claim 13,wherein the groove of the first film is formed by at least the firstinsulating film and the second insulating film, and the groove of thesecond film is formed by at least the third insulating film and thefourth insulating film.
 15. The device according to claim 14, whereinthe second insulating film has a part between the first portion and thefirst substrate
 16. The device according to claim 11, wherein the firststructure includes an aluminum wire, the aluminum wire is between thefirst portion and the first substrate, and the aluminum wire is betweenthe second insulating film and the first substrate.
 17. The deviceaccording to claim 11, wherein the second structure includes a copperwire, the copper wire is between the second portion and the secondsubstrate, a diffusion preventing film is arranged between the fourthinsulating film and the copper wire, and the second portion is incontact with the copper wire.
 18. The device according to claim 11,wherein the first insulating film is an inorganic insulating film. 19.The device according to claim 11, wherein the first dielectric materialis silicon nitride or silicon carbide, and the second dielectricmaterial is silicon oxide.
 20. A system comprising: the device accordingto claim 11; and a processor which processes a digital data based on asignal outputted from the device.
 21. A device comprising: a firstsubstrate; a second substrate which overlaps the first substrate; afirst structure which is between the first substrate and the secondsubstrate, the first structure including a first film of a dielectricmaterial and a first portion of a conductive material, the first portionbeing in a groove of the first film; and a second structure which isbetween the first structure and the second substrate, the secondstructure including a second film of a dielectric material and a secondportion of a conductive material, the second portion being in a grooveof the second film, wherein the first film is bonded to the second film,and the first portion is bonded to the second portion, and wherein thefirst portion includes a first conductive portion of a first conductivematerial, the first portion includes a first conductive film of a secondconductive material other than the first conductive material, the firstconductive film is between the first conductive portion and the firstfilm.
 22. The device according to claim 21, wherein the second portionincludes a second conductive portion of a third conductive material, thesecond portion includes a second conductive film of a fourth conductivematerial other than the third conductive material, the third conductivefilm is between the second conductive portion and the second film. 23.The device according to claim 22, wherein the first conductive film hasa part between the first conductive portion and the first substrate, andthe second conductive film has a part between the second conductiveportion and the second substrate.
 24. The device according to claim 23,wherein the first structure includes a first wire between the firstportion and the first substrate, and the second structure includes asecond wire between the second portion and the second substrate.
 25. Thedevice according to claim 24, wherein the first wire is primarilycomposed of aluminum, and the second wire is primarily composed ofcopper.
 26. The device according to claim 21, wherein the firststructure includes an aluminum wire and a layer of a barrier metal, thealuminum wire is between the first portion and the first substrate, alayer of a barrier metal is arranged between the second insulating filmand the aluminum wire, and the first portion is in contact with thealuminum wire.
 27. The device according to claim 21, wherein the secondstructure includes a copper wire, the copper wire is between the firstportion and the first substrate, and the first portion is in contactwith the copper wire.
 28. The device according to claim 21, wherein thefirst film includes an insulating film which is a silicon nitride filmor a silicon carbide film, the groove of the first film is formed by atleast the insulating film, and the first conductive film has a partbetween the insulating film and the first conductive portion.
 29. Thedevice according to claim 21, wherein the first conductive material iscopper, and the second conductive material is tantalum or tantalumnitride.
 30. A system comprising: the device according to claim 21; anda processor which processes a digital data based on a signal outputtedfrom the device.